In the drilling of or producing of any offshore well there exists the risk that there will be a blowout. A blowout in effect constitutes the presence of an excessive amount of gas pressure which is acting on the fluid reservoir into which the well is communicated. The result is that often the gas pressure on the fluids is so great as to overcome the resisting pressure of the various control valves.
As a matter of general practice, the drilling of any well bore to produce hydrocarbons whether gaseous or liquid, entails the use of certain safety equipment. More particularly, this safety equipment requires the presence of control valves which are firmly attached to the well casing whereby to control the passage of fluid upwardly through the casing.
Often these flow control valves are incorporated into a Christmas tree arrangement such that upward movement of hydrocarbons can be regulated to a desired flow rate. During a drilling operation however, the control valves are supplemented by blowout preventer apparatus. The latter is a form of equipment which operates either automatically or otherwise to control or close off a well bore. This is done so that the well can be closed in even though the drill string or parts of the latter remain in the bore.
In some instances, the well might be uncontrolled due to an unconsolidated substrate that is not particularly firm. Thus, although the well might be capped or otherwise blocked, the hydrocarbons can nonetheless be forced out through fissures formed in the earth by virtue of the great gas pressure. In any event, it is desirable while suitable means is being determined for closing in a well, that the uncontrolled escape of effluents be regulated or at least contained within some confining apparatus.
It is appreciated that the escaping effluent is not merely the upward passage of crude oil or liquids. A major factor of concern is the escape of large quantities of gas which have caused the blowout. In the instance of the latter, as the gas escapes from the earth it will expand into the water, and thereafter the rising bubbles will expand even further.
The result of this rapid passage of large quantities of gas through the water usually causes a severe turbulence in the latter. The surface of the water will not only be bubbling and turmoiled, but the area or corridor between the well bore and the water's surface, will likewise exhibit considerable turbulence.
A problem normally encountered in confining such wells by a bell or other similarly shaped enclosure resides in the inability to position the closure means due to the water turbulence. In effect, the rising gases tend to upset and disrupt any descending body which might otherwise be lowered to the ocean floor for the purpose of covering or enclosing the uncontrolled wellhead.
Toward overcoming this problem, the instant apparatus is addressed to a bell-like member particularly adapted to be drawn to the ocean floor and thereafter positioned in place. This is achieved through the preplacing of a number of anchors about the well. The anchors serve to guide a plurality of pull down cables which in turn are attached to the enclosing bell and which are led to the surface of the water. As a result, the entire operation can be conducted from several barges positioned about, but spaced from the turbulent water area.
Operationally, the confining bell is lowered toward the uncontrolled well, yet is spaced sufficiently distant from the latter as not to be affected by the troubled waters. When the bell reaches the ocean floor it is drawn laterally, by manipulation of the control cables, toward the well such that the bell can be properly positioned with respect to the well.
Thereafter, rising gases, as well as liquid hydrocarbons will be partially confined and directed upward through the bell and into an elongated conduit. From the latter, the fluids can be led to a separation barge or other equipment at the water's surface where the water, oil and gas will be separated.
It is therefore an object of the invention to provide an apparatus of the type contemplated which is particularly adapted to be lowered to the ocean floor to form at least a partial closure over an uncontrolled well.
A further object is to provide an apparatus of the type contemplated which can be controlled entirely from the water's surface thereby avoiding excessive risks to workmen.
Another object is to provide a well control device which is capable of confining rapidly emitted gases and fluids from an uncontrolled offshore well such that the effluent can be collected and separated into discrete components.